Route matching filter not exported
Nico Schottelius
nico.schottelius at ungleich.ch
Fri May 17 16:34:49 CEST 2024
Hello bird users,
I've a strange case in which a router does not export routes that are
matched by the export filter. I am using the filter "static_and_bgp"
inside our iBGP sessions:
--------------------------------------------------------------------------------
bird> show protocol all ibgp_server137
Name Proto Table State Since Info
ibgp_server137 BGP --- up 2024-05-12 Established
BGP state: Established
Neighbor address: 2a0a:e5c0:0:b::89
Neighbor AS: 199553
Local AS: 199553
Neighbor ID: 91.194.139.7
Local capabilities
Multiprotocol
AF announced: ipv4 ipv6
Route refresh
Extended next hop
IPv6 nexthop: ipv4
Graceful restart
4-octet AS numbers
Enhanced refresh
Long-lived graceful restart
Neighbor capabilities
Multiprotocol
AF announced: ipv4 ipv6
Route refresh
Extended next hop
IPv6 nexthop: ipv4
Graceful restart
4-octet AS numbers
Enhanced refresh
Long-lived graceful restart
Session: internal AS4
Source address: 2a0a:e5c0:0:b::91
Hold timer: 197.601/240
Keepalive timer: 4.476/80
Channel ipv6
State: UP
Table: master6
Preference: 100
Input filter: ACCEPT
Output filter: static_and_bgp
Routes: 204647 imported, 2 exported, 204647 preferred
Route change stats: received rejected filtered ignored accepted
Import updates: 6285634 0 0 3097 6282537
Import withdraws: 3559063 0 --- 189 3558874
Export updates: 6768067 6387362 37995 --- 342710
Export withdraws: 3370586 --- --- --- 334365
BGP Next hop: 2a0a:e5c0:0:b::91 fe80::2f0:cbff:fefe:b70c
IGP IPv6 table: master6
Channel ipv4
State: UP
Table: master4
Preference: 100
Input filter: ACCEPT
Output filter: static_and_bgp
Routes: 947321 imported, 3 exported, 947318 preferred
Route change stats: received rejected filtered ignored accepted
Import updates: 22332349 0 0 2202 22330147
Import withdraws: 15475598 0 --- 343 15475255
Export updates: 24213451 22602108 0 --- 1611343
Export withdraws: 14527850 --- --- --- 1598351
BGP Next hop: 2a0a:e5c0:0:b::91 fe80::2f0:cbff:fefe:b70c
IGP IPv4 table: master4
IGP IPv6 table: master6
--------------------------------------------------------------------------------
As you can see, the router in question only exports 2 IPv6 routes and 3
IPv4 routes and uses the filter "static_and_bgp".
When I check the route count matching the filter, the numbers look very
different:
--------------------------------------------------------------------------------
bird> show route filter static_and_bgp count
2841971 of 2841971 routes for 947325 networks in table master4
613945 of 613983 routes for 204686 networks in table master6
Total: 3455916 of 3455954 routes for 1152011 networks in 2 tables
bird>
--------------------------------------------------------------------------------
And looking at some routes in detail:
--------------------------------------------------------------------------------
bird> show route filter static_and_bgp
Table master4:
0.0.0.0/0 unicast [ibgp_server137 11:03:59.224 from 2a0a:e5c0:0:b::89] * (100/?) [AS209898i]
via fe80::3eec:efff:fed2:d1e4 on eth0
unicast [outgoing_server120 08:53:28.568] (100) [AS209898i]
via 2a0a:e5c0:31:4::1 on tun1
unicast [outgoing_server121 08:55:44.577] (100) [AS209898i]
via 2a0a:e5c0:32:4::1 on tun0
49.14.107.0/24 unicast [ibgp_server137 11:03:59.224 from 2a0a:e5c0:0:b::89] * (100/?) [AS45271i]
via fe80::3eec:efff:fed2:d1e4 on eth0
unicast [outgoing_server120 08:55:43.482] (100) [AS45271i]
via 2a0a:e5c0:31:4::1 on tun1
unicast [outgoing_server121 08:55:44.577] (100) [AS45271i]
via 2a0a:e5c0:32:4::1 on tun0
181.123.200.0/22 unicast [ibgp_server137 11:03:59.224 from 2a0a:e5c0:0:b::89] * (100/?) [AS23201i]
via fe80::3eec:efff:fed2:d1e4 on eth0
unicast [outgoing_server120 08:55:30.698] (100) [AS23201i]
via 2a0a:e5c0:31:4::1 on tun1
unicast [outgoing_server121 08:55:44.577] (100) [AS23201i]
via 2a0a:e5c0:32:4::1 on tun0
88.218.186.0/24 unicast [ibgp_server137 11:03:59.224 from 2a0a:e5c0:0:b::89] * (100/?) [AS62240i]
via fe80::3eec:efff:fed2:d1e4 on eth0
unicast [outgoing_server120 08:55:22.108] (100) [AS62240i]
via 2a0a:e5c0:31:4::1 on tun1
unicast [outgoing_server121 08:55:44.577] (100) [AS62240i]
via 2a0a:e5c0:32:4::1 on tun0
--------------------------------------------------------------------------------
I verified that 2a0a:e5c0:31:4::1 and 2a0a:e5c0:32:4::1 are resolvable
via OSPF on the other routers:
--------------------------------------------------------------------------------
bird> show route for 2a0a:e5c0:32:4::1
Table master6:
2a0a:e5c0:32:4::/64 unicast [ospf6 2024-05-12] * I (150/20) [91.194.139.99]
via fe80::2f0:cbff:fefe:b70c on eth2
unicast [outgoing_server120 11:11:16.933] (100) [AS209898i]
via 2a0a:e5c0:31:2::1 on oserver120
bird>
--------------------------------------------------------------------------------
But this should not matter at this stage, because the originating router
does not seem to try to send this route.
What am I missing, why is a route matching the same filter not being
exported?
Best regards,
Nico
--
Sustainable and modern Infrastructures by ungleich.ch
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